Yes, it should definitely impact your decision. Assessments being paid by the owner will not be an issue regarding your purchase of that unit. That is what the owner is supposed to do even if renting that particular unit to another party.
I can tell you the issue is mostly related to financing. If you are a cash buyer, then half of the problems and issues are negated. Different banks/investors have different requirements depending upon the individual risk assement by that bank/investor. Fannie Mae may say less than 50% is OK. But bank/investor A may set more restrictive rules in addition to Fannie/Freddie rules in that no more than 10% investor concentration is allowed, Bank B 20% and Bank C 25% for example purposes. As far as which percentage investor concentration should be considered when attempting to narrow down from which condo project you would purchase depends much upon your timeframe to purchase. If buying within a month, likely the 50% investor concentration rule is still available with a couple of banks so you could search through quite a few additional condo projects that have higher rental percentages. If 6 months is your time frame, be conservative and waive at 10%. The reason being is this high percentage investor concentration of 50% which is still available now (a "window" of opportunity we'll call it) will narrow as time passes and may become much more restrictive...and that's due to all of the issues prevelent within the markets of which you already know (economic downturn, liquidity crisis, subsequent housing declines etc).
Have your realtor or attorney (or yourself) contact the association or management office - of a project retaining a unit in which you are interested purchasing - to confirm in advance what the rental percentage is. It may not be completely accurate but if the building is 30% rented due to sales lag, it may be time to consider other projects.
It would be to your advantage to work with a correspondent mortgage lender such as us when the time comes. Therein lies the ability for the multiple investor relationships to be sifted through in order to isolate a product or program that will accomodate financing of the project without issue. Hope this helps. We appreciate you as a customer and consumer alike and look forward to helping any way we can. Contact me if needed CJ.